134 research outputs found

    Insights into the Mind of a Trojan Designer: The Challenge to Integrate a Trojan into the Bitstream

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    The threat of inserting hardware Trojans during the design, production, or in-field poses a danger for integrated circuits in real-world applications. A particular critical case of hardware Trojans is the malicious manipulation of third-party FPGA configurations. In addition to attack vectors during the design process, FPGAs can be infiltrated in a non-invasive manner after shipment through alterations of the bitstream. First, we present an improved methodology for bitstream file format reversing. Second, we introduce a novel idea for Trojan insertion

    Brewing of filter coffee

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    We report progress on mathematical modelling of coffee grounds in a drip filter coffee machine. The report focuses on the evolution of the shape of the bed of coffee grounds during extraction with some work also carried out on the chemistry of extraction. This work was sponsored by Philips who are interested in understanding an observed correlation between the final shape of the coffee grounds and the quality of the coffee. We used experimental data gathered by Philips and ourselves to identify regimes in the coffee brewing process and relevant regions of parameter space. Our work makes it clear that a number of separate processes define the shape of the coffee bed depending on the values of the parameters involved e.g. the size of the grains and the speed of fluid flow during extraction. We began work on constructing mathematical models of the redistribution of the coffee grounds specialised to each region and on a model of extraction. A variety of analytic and numerical tools were used. Furthermore our research has progressed far enough to allow us to begin to exploit connections between this problem and other areas of science, in particular the areas of sedimentology and geomorphology, where the processes we have observed in coffee brewing have been studied

    Nova light curves from the Solar Mass Ejection Imager (SMEI) - II. The extended catalogue

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    We present the results from observing nine Galactic novae in eruption with the Solar Mass Ejection Imager (SMEI) between 2004 and 2009. While many of these novae reached peak magnitudes that were either at or approaching the detection limits of SMEI, we were still able to produce light curves that in many cases contained more data at and around the initial rise, peak, and decline than those found in other variable star catalogs. For each nova, we obtained a peak time, maximum magnitude, and for several an estimate of the decline time (t2). Interestingly, although of lower quality than those found in Hounsell et al. (2010a), two of the light curves may indicate the presence of a pre-maximum halt. In addition the high cadence of the SMEI instrument has allowed the detection of low amplitude variations in at least one of the nova light curves

    Dual Role for Pilus in Adherence to Epithelial Cells and Biofilm Formation in Streptococcus agalactiae

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    Streptococcus agalactiae is a common human commensal and a major life-threatening pathogen in neonates. Adherence to host epithelial cells is the first critical step of the infectious process. Pili have been observed on the surface of several gram-positive bacteria including S. agalactiae. We previously characterized the pilus-encoding operon gbs1479-1474 in strain NEM316. This pilus is composed of three structural subunit proteins: Gbs1478 (PilA), Gbs1477 (PilB), and Gbs1474 (PilC), and its assembly involves two class C sortases (SrtC3 and SrtC4). PilB, the bona fide pilin, is the major component; PilA, the pilus associated adhesin, and PilC, are both accessory proteins incorporated into the pilus backbone. We first addressed the role of the housekeeping sortase A in pilus biogenesis and showed that it is essential for the covalent anchoring of the pilus fiber to the peptidoglycan. We next aimed at understanding the role of the pilus fiber in bacterial adherence and at resolving the paradox of an adhesive but dispensable pilus. Combining immunoblotting and electron microscopy analyses, we showed that the PilB fiber is essential for efficient PilA display on the surface of the capsulated strain NEM316. We then demonstrated that pilus integrity becomes critical for adherence to respiratory epithelial cells under flow-conditions mimicking an in vivo situation and revealing the limitations of the commonly used static adherence model. Interestingly, PilA exhibits a von Willebrand adhesion domain (VWA) found in many extracellular eucaryotic proteins. We show here that the VWA domain of PilA is essential for its adhesive function, demonstrating for the first time the functionality of a prokaryotic VWA homolog. Furthermore, the auto aggregative phenotype of NEM316 observed in standing liquid culture was strongly reduced in all three individual pilus mutants. S. agalactiae strain NEM316 was able to form biofilm in microtiter plate and, strikingly, the PilA and PilB mutants were strongly impaired in biofilm formation. Surprisingly, the VWA domain involved in adherence to epithelial cells was not required for biofilm formation

    Proteomic Modeling for HIV-1 Infected Microglia-Astrocyte Crosstalk

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    Background: HIV-1-infected and immune competent brain mononuclear phagocytes (MP; macrophages and microglia) secrete cellular and viral toxins that affect neuronal damage during advanced disease. In contrast, astrocytes can affect disease by modulating the nervous system’s microenvironment. Interestingly, little is known how astrocytes communicate with MP to influence disease. Methods and Findings: MP-astrocyte crosstalk was investigated by a proteomic platform analysis using vesicular stomatitis virus pseudotyped HIV infected murine microglia. The microglial-astrocyte dialogue was significant and affected microglial cytoskeleton by modulation of cell death and migratory pathways. These were mediated, in part, through F-actin polymerization and filament formation. Astrocyte secretions attenuated HIV-1 infected microglia neurotoxicity and viral growth linked to the regulation of reactive oxygen species. Conclusions: These observations provide unique insights into glial crosstalk during disease by supporting astrocytemediated regulation of microglial function and its influence on the onset and progression of neuroAIDS. The results open new insights into previously undisclosed pathogenic mechanisms and open the potential for biomarker discovery an

    A Medicinal Chemist’s Guide to Molecular Interactions

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    Evaluating of the usefulness of nursery Prunus tomentosa Thunb. as a dwarf rootstock for plum

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    W doświadczeniach porównywano efektywność rozmnażania generatywnego wisienki kosmatej i ałyczy oraz przydatność tych podkładek w produkcji okulantów śliw odmian: 'Cacanska Najbolja' i 'Valor'. Nasiona wisienki kosmatej miały procent wschodów niższy od ałyczy. Siewki wisienki kosmatej miały umiarkowaną siłę wzrostu, mniejszą liczbę rozgałęzień bocznych i większą korzeni szkieletowych. Wydajność okulantów odmiany 'Cacanska Najbolja' była istotnie większa na wisience kosmatej niż na ałyczy, a odmiany 'Valor' podobna na obu podkładkach. Wzrost okulantów śliwy na podkładce wisienki kosmatej był istotnie słabszy. Fakt ten miał wpływ na mniejszą ich zgodność z Polską Normą.The experiments aimed at comparison of the effectiveness of generative propagation of Prunus tomentosa and Prunus cerasifera and their usefulness as the rootstocks for young plum trees for nursery production. Emergence of Prunus tomentosa seedlings was lower as compared to Prunus cerasifera. The seedlings of Prunus tomentosa grew moderately, having less lateral branches and more roots. Young plum trees of 'Cacanska Najbolja' were more efficient on Prunus tomentosa than on Prunus cerasifera, whereas in case of 'Valor' the efficiency was similar on both rootstocks. The growth of young plum trees on Prunus tomentosa rootstock was significantly poorer. This fact influenced their less conformity with the Polish Standards
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